Background. Adequate rotation of femoral component in total knee arthroplasty(TKR) is mandatory for preventing numerous adverse sequelae. The transepicondylar axis has been a well-accepted reference for femoral component rotation in the measured resection technique. In this technique, measured resection is performed referenced off the tibial cut - perpendicular to the tibial mechanical axis with the knee in 90 ° of flexion. However, to the best of our knowledge, it is not known whether this technique apply well to a knee with tibia vara. This study evaluates the reliability of the transepicondylar axis as a rotational landmark in knees with tibia vara. Methods. We selected 101 osteoarthritis knees in 84 symptomatic patients(mean age: 69.24 ± 5.68) with proximal tibia vara (Group A). Group A was compared with 150 osteoarthritic knees without tibia vara in 122 symptomatic patients (mean age: 69.51 ± 6.01) (Group B). The guide line for selection of all these knees were based on the degree of tibia vara angle (TVA) which was formed by line perpendicular to epiphysis and by anatomical axis of the tibia - all measured in radiographs of the entire lower limb. Magnetic resonance imaging (MRI) axial images with most prominent part of both femoral condyles were used for measurement of transepicondylar axis(TE), anteroposterior axis(AP) and posterior condylar axis(PC). Results. The mean TVA of group A was 8.94° ± 3.11 and group B was 1.24° ± 0.85. The TE line in Group A showed 6.09 ° ± 1.43 of external rotation, relative to PC. This did not show statistical difference compared with 5.95 ° ± 1.58 in Group B (p=0.4717). The AP line in Group A showed 6.06 ° ± 1.93 of external rotation, relative to the line perpendicular to PC. This was statistically significant when compared to 5.44 ° ± 2.13 in Group B (p=0.020). Conclusion. There is no difference between knees without tibia vara compared those with tibia vara with regards to transepicondylar axis. In addition, both groups have almost identical external rotation of approximately 6 °. The AP axis was only approximately 0.5 ° difference between the two groups. The distal femoral geometry was not affected by tibia vara deformity, that is, there were no hypoplastic or hyperplastic deformities of medial femoral condyle in osteoarthritic knees with tibia vara. The use of transepicondylar axes in determining femoral rotation may produce flexion asymmetry in knees with proximal tibia vara. So, It should be pointed out that more attention should be paid on femoral component rotation and flexion gap balancing in knees with proximal tibial vara

Introduction

Patellofemoral complications remain a very common post-operative problem in association with total knee arthoplasty (TKA). As malrotation of the femoral component is often considered crucial for the outcome, we analyzed absolute rotational femoral alignment in relation to patellar tracking pre- and postoperatively and matched the results with the two year functional outcome.

Introduction. Total knee arthroplasty is an established and successful operation. In up to 10% of patients who undergo total knee arthroplasty continue to complain of pain [1]. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful total knee arthroplasty. Methods. We reviewed 56 painful total knee replacements and compared these to 59 pain free total knee replacements. Datum gathered from case notes and radiographs using a prospective orthopaedic database to identify patients. The age, sex, preoperative Oxford score and BMI, postoperative Oxford score and treatments recorded. The CT information recorded was limb alignment, tibial component rotation, femoral component rotation and combined rotation. Results. The two cohorts of patients had similar demographics. The mean limb alignments were 1.7 degrees varus and 0.01 degrees valgus in the painful and control groups respectively. A significant difference in tibial component rotation was identified between the groups with 3.2 degrees of internal rotation in the painful group compared to 0.5 degrees of external rotation in the control group (p=0.001). A significant difference in femoral component rotation was identified between the groups with 3.8 degrees of internal rotation in the painful group compared to 1.1 degrees of external rotation in the control group (p=0.001). A significant difference in the combined component rotation was identified between the groups with 6.8 degrees of internal rotation in the painful group compared to 1.7 degrees of external rotation in the control group (p=0.001). Conclusion. We have identified significant internal rotation in a patient cohort with painful total knee arthroplasty when compared to a control group. There was internal rotation of the tibial component, femoral component and combined rotation. This is the largest comparison series currently in the literature

Total knee arthroplasty (TKA) is an established and successful operation. However patient satisfaction rates vary from 81 to 89% 1,2,3. Pain following TKA is a significant factor in patient dissatisfaction 1. Many causes for pain following total knee arthroplasty have been identified 4 but rates of unexplained pain vary from 4 to 13.1% 5,6. Recently computerised tomography (CT) has been used to assess the rotational profile of both the tibial and femoral components in painful TKA. We reviewed 57 patients with an unexplained painful following TKA and compared these to a matched control group of 60 patients with TKA. Datum gathered from case notes and radiographs using a prospective database to identify patients. The CT information recorded was limb alignment, tibial component rotation, and femoral component rotation and combined rotation. The two matched cohorts of patients had similar demographics. A significant difference in tibial, femoral and combined component rotation was identified between the groups. The following mean rotations were identified for the painful and control groups respectively. Tibial rotation was 3.46 degrees internal rotation (IR) compared to 2.50 degrees external rotation (ER)(p=0.001). Femoral rotation was 2.30 IR compared to 0.36 ER(p=0.02). Combined rotation was 7.08 IR compared to 2.85 ER(p=0.001). This is the largest study presently in the literature. We have identified significant internal rotation in a patient cohort with unexplained painful TKA when compared to a matched control group. Internal rotation of the tibial component, femoral component and combined rotation was identified as a factor in unexplained pain following TKA